Generally, in a digital communication system, transmitter parameters, including an eye diagram crossing point of a transmitter, a driving amplitude, a Von (Voltage-On) level of an EA (electro absorption) modulated laser and the like, are important factors influencing the performance of the system.
Taking the eye diagram crossing point of a transmitter as an example, if the eye diagram crossing point of the transmitter is properly lowered, an average power of signals will be reduced as well. When the average power is invariant, the power of a code “1” signal with a lower eye diagram crossing point is higher than that of a code “1” signal with a higher eye diagram crossing point, that is, the code “1” signal with the lower eye diagram crossing point has a better noise resistant performance and is superior in signal-to-noise ratio (SNR for short) tolerance and receiving sensitivity. However, if the eye diagram crossing point is too low, the range of code “1” will be narrowed down and the redundancy space for the decision of the code “1” will be reduced, which may result in occurrence of an error in decision of the code “1” and an increase in bit error rate.
Taking the driving amplitude for another example, generally, the larger the driving amplitude is, the higher the extinction ratio is, and the higher the power ratio of “1” to “0” is, the better the noise resistant performance during transmission is and therefore the better the transmission performance is. However, if the driving amplitude is too large, the signal outputted from a drive will be distorted and degraded, and the transmission performance of the system will be consequentially degraded.
Likewise, as to the Von level of an EA modulated laser and various other adjustable parameters, there exists an optimal operating point which can optimize the transmission performance of a system. Therefore, a rational optimization for transmitter parameters is necessary in a digital communication system.
However, in existing systems, a transmitter parameter is not optimized but adjusted to a fixed empirical value, which generally cannot guarantee the set transmitter parameter being optimal.
No effective solution has been provided for transmitter parameter optimization in existing related technologies.